Pulmonary Hypertension (cont.)

George Schiffman, MD, FCCP

Dr. Schiffman received his B.S. degree with High Honors in biology from Hobart College in 1976. He then moved to Chicago where he studied biochemistry at the University of Illinois, Chicago Circle. He attended Rush Medical College where he received his M.D. degree in 1982 and was elected to the Alpha Omega Alpha Medical Honor Society. He completed his Internal Medicine internship and residency at the University of California, Irvine.

Siamak N. Nabili, MD, MPH

Dr. Nabili received his undergraduate degree from the University of California, San Diego (UCSD), majoring in chemistry and biochemistry. He then completed his graduate degree at the University of California, Los Angeles (UCLA). His graduate training included a specialized fellowship in public health where his research focused on environmental health and health-care delivery and management.

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

How is pulmonary hypertension diagnosed?

The first step in diagnosis of pulmonary hypertension is to clinically
suspect it. This may be done as part of an evaluation of another disease that
can lead to pulmonary hypertension (such as scleroderma or chronic obstructive
pulmonary disease), or based on patients and signs and symptoms as described
above.

Many tests, such as echocardiogram, may be performed that
may give clues to
the possibility of pulmonary hypertension. It is important that a Doppler study
be performed with the echocardiogram, which enables the doctor to approximate
the pulmonary artery pressures. These values are calculated based on the sound
quality of the wave approaching and leaving the echocardiogram machine
sensor/probe. This is based on the principle that explains why the sound of an
approaching and then passing train varies.

But the gold standard (the best test
available) is right heart catheterization. This test entails inserting a
catheter through the groin into the femoral vein, a large
vein in the lower body (or under the collar bone or in the upper arm or neck into a large
vein in the upper body) and advancing it to the right side of the heart. The
catheter is connected to a device that can monitor and measure blood pressure in
the right side of the heart and pulmonary arteries.

During right heart catheterization, oxygen levels are measured during various positions of the catheter in the pulmonary circulation. This can help determine if a congenital or acquired hole has formed in the heart contributing to the elevated pulmonary pressures. Certain medications or activities can be administered or performed during the procedure to help with the assessment. Nitric oxide can be inhaled and in certain forms of PAH a dramatic improvement in pressures can occur suggesting specific treatment options such as the use of calcium channel blocker medication. Some patients have an exaggerated pulmonary pressure response to exercise and this too can be measured by utilizing arm exercise during the procedure.
Titration of medications for pulmonary hypertension while the he catheter is in
place can help monitor the response to treatment and assist in optimizing
therapy. This can assist in providing individualized therapy for patients with
this complex disease.

Pulmonary hypertension is defined as the mean pulmonary artery blood pressure
greater than 25 millimeter of mercury (mmHg) measured by right heart
catheterization. The pressures can be much higher than 25 mmHg in some people.
Therefore, the pulmonary hypertension can be labeled as mild, moderate, or
severe based on the pressures. Mean arterial pressure is two-thirds of the
difference between systolic and diastolic blood pressure (systolic is the upper
number and diastolic is the lower number in measuring blood pressure). Normally, the pulmonary blood pressure is much lower
pressure system than the systemic
blood pressure (which is usually measured with a blood pressure cuff).

What tests other than right heart catheterization may be used in diagnosing pulmonary hypertension?

Other tests available for diagnosing pulmonary
hypertension include electrocardiogram (ECG,
EKG), chest
X-ray, and echocardiogram.
An ECG may show some abnormalities that may be suggestive of right heart
failure. Chest x-ray may also show enlargement of the chambers of the right
heart. And echocardiogram (ultrasound of the heart) shows ultrasound images of the heart and can detect
evidence of right heart failure and with the use of Doppler (as described
previously) can estimate pressures in the pulmonary artery. These tests, in the right clinical setting, are very useful in
diagnosing and managing pulmonary hypertension.

Other tests may be useful in evaluating the conditions leading to secondary pulmonary hypertension. For example, a ventilation-perfusion scan (V/Q scan) can suggest blood clots in the pulmonary arteries or sometimes a
CT scan of the chest can be used. The chest CT scan can detect pulmonary arterial clots, but also can show abnormalities of the lung tissue and surrounding structures that can contribute to pulmonary hypertension. A pulmonary function testing can be useful in diagnosing chronic obstructive pulmonary disease (COPD)
and monitor disease progression. This test can be used to detect many aspects of lung function including airflow and evidence of obstruction, lung volumes, and the capacity for the lung to extract oxygen from the air.